The calendar has officially turned to fall and the annual show that follows is beginning across south central Iowa.

Professor of Biology at Central College Paul Weihe says he looks forward to the return of leaves changing colors in the coming weeks, with two main factors in why that happens.

“One of those would be sort of the yellows, oranges, and golds, and those really are pigments that were present in the plant all along, but those were masked by the green, and that’s what most of us were taught about how color change works,” he says. “But there’s the whole category of colors which are the reds, purples, and some of those really vibrant ones–those are actually produced in response to the changing conditions as we enter the autumn, so those are really acting as a sunscreen to protect the tissues within the leaf, while the tree is recovering some of those materials that the leaf is made out of for recycling and use the following year.”

Weihe says the past several fall seasons have started with drought, and that’s the case again in 2023 — which will likely shorten the window for the color change and have it start a bit sooner.

According to the Iowa Department of Natural Resources, the peak viewing season in south central Iowa typically is in the middle two weeks of October. .

Hear more about the annual changing of the leaves on today’s Let’s Talk Pella.